This invention relates to a color-changeable cement composition for dental use. Particularly, this invention relates to a color-changeable cement composition which can change the color thereof upon setting of the cement and which enables one to easily judge the state or degree of setting by visual observation.
Now, cement for dental use or dental cement is one of the most prevailing materials that are used clinically by dentists for various applications. For example, it is used for luting of prostheses or orthodontic bands. It is also used for filling the cavity formed by dental caries or for building up, lining, indirect capping, matrix or pit and fissure sealing.
Dental cements widely used at present include zinc phosphate cement, polycarboxylate cement, glass ionomer cement, zinc oxide-eugenol cement, etc. Usually, these cements are used as a mixture of two components, e.g., a mixture of powder and liquid, mixed with each other. The cements are prepared so that they can undergo initial setting within a few minutes after the start of mixing. Therefore, when these cements are used, it is necessary to complete processing or operation while there is an ample allowance in operation, that is, while the mixed cement still has a flowability.
However, it is practically difficult to judge only by visual observation whether or not the mixed dental cement slurry is still in a state where it could be clinically manipulated. It is also practically difficult to judge the extent of area where a glass ionomer cement is actually applied since the glass ionomer cement has a color of crown, when it is used for lining or pit and fissure sealing, although it is highly aesthetic. This is because the glass ionomer cement is translucent and has a color closely resembling that of teeth, which causes the difficulty of discriminating or judging the cement from the tooth substance, resulting in that it is difficult to judge if the cement is applied all over the area intended to be applied, and it is often the case that application is performed on area wider than necessary. Further, when the cement is used for luting of prostheses such as crown, inlay and bridge, it is necessary to eliminate excess cement slurry which is crowded out. In this case, the glass ionomer cement is also difficult to find out where it is crowded out.